On 31 August 2026, Vanuatu submitted an Application to the International Court of Justice, with the intention of instituting proceedings against France. The dispute concerns the question of sovereignty over the uninhabited Umaenupne (Matthew) and Umaeneg/Leka (Hunter) Islands and the maritime boundary between Vanuatu and the French territory of New Caledonia. While the islands themselves are tiny and uninhabited, they are “deeply sacred and intrinsically linked to Vanuatu’s cultural identity”. Moreover, as an Archipelagic State, Vanuatu would be entitled to exercise sovereignty not only over the islands but also over the interconnecting waters which lie between its territory and the single maritime boundary Vanuatu seeks to establish. Don Rothwell has neatly explained the substantive issues in the case here. In this post, I will instead focus on explaining the basis of jurisdiction relied upon by Vanuatu. Or rather, the proposed basis. Because you won’t find Vanuatu v. France listed anywhere on the Court’s website just yet. Vanuatu has invoked one of the lesser-known grounds of jurisdiction in this proceeding – forum prorogatum – meaning that no case will come into being unless and until France decides to accept it.
Forum Prorogatum: What Is It?
The Court cannot hear a dispute without the consent of the States in question. Ordinarily, jurisdiction is based on consent which has been expressed prior to the institution of proceedings, by way of one of three routes: an optional clause declaration, a compromissory clause in a treaty, or a special agreement between the parties. Forum prorogatum is quite different. It enables the jurisdiction of the Court to be perfected after the filing of the Application. In other words, the Applicant submits the dispute to the Court knowing that no grounds of jurisdiction exist and simply hopes that the intended Respondent agrees to the Court hearing the case. The decision on whether the matter proceeds rests entirely with that State.
Forum prorogatum jurisdiction was not built into the Statute of either the Court nor its interwar predecessor, the Permanent Court of International Justice. It is instead found in the Rules of Court. Article 38(2) of the Rules requires that Applicants specify “the legal grounds upon which the jurisdiction of the Court is said to be based”. Paragraph 5 then particularises the requirements of forum prorogatum:
“When the applicant State proposes to found the jurisdiction of the Court upon a consent thereto yet to be given or manifested by the State against which such application is made, the application shall be transmitted to that State. It shall not however be entered in the General List, nor any action be taken in the proceedings, unless and until the State against which such application is made consents to the Court’s jurisdiction for the purposes of the case.”
Notably, however, this provision was only included in the Court’s Rules following a major overhaul completed in 1978. Prior to this, the use of forum prorogatum was a practice that had developed via the Court’s case law; a small ‘r’ rule eventually transposed into a capital ‘R’ Rule proper. The Permanent Court recognised early on in Mavrommatis that a defect in jurisdiction can be cured by consent expressed after the filing of the Application (in that case, by way of a separate instrument that came into force by the date of the hearing). It adopted a similar approach in the Minority Schools case, where it held that arguing the merits constituted consent to jurisdiction. Indeed, the Court’s first ever case – Corfu Channel – proceeded (somewhat dubiously) on the basis of consent to jurisdiction that was expressed after the institution of proceedings. Naturally, however, forum prorogatum cannot be relied upon as a basis for jurisdiction where the Respondent State appears before the Court for the sole purpose of arguing preliminary objections.
The Low Success Rate of Article 38(5)
A surprising number of States have attempted to make use of forum prorogatum as a basis for jurisdiction. Vanuatu’s Application by my count is the 25th to date. Mali relied upon it in 2025 in proceedings against Algeria, which have not at the time of writing gone any further. Prior to that, Argentina against the United States and the Marshall Islands against six States regarding nuclear weapons in 2014. It can be difficult to find information about such instances; since the 1978 revision of the Rules the Court has not entered forum prorogatum cases in its General List. Rather, it informs the public of the existence of an Application by way of a press release and does not place any further documentation on the Court website until jurisdiction is perfected by the Respondent’s acceptance. This practice came about as result of what some called an “abusive” (p.175) use of the principle during the 1950s, when eight forum prorogatum cases were filed, six of which were Cold War needling between the United States and the USSR. Those applications all had to be entered in the General List and when the invitations to accept the jurisdiction were inevitably refused, the Court had to make formal orders directing the removal of the cases from the List. The current procedure is significantly more streamlined.
Of the 25 attempts to engage forum prorogatum only two have progressed under the express terms of Article 38(5) and both times, France was the Respondent. In the first case, Certain Criminal Proceedings in France (Republic of the Congo v. France), while France accepted jurisdiction Congo’s request for provisional measures was denied and eventually in 2010 the case was discontinued after several rounds of written pleadings. In Certain Questions of Mutual Assistance in Criminal Matters (Djibouti v. France), France’s consent to jurisdiction meant that the case had only one round – on the merits – and the Court’s judgment was issued less than two years after the filing of the Application. If nothing else, forum prorogatum can provide a very efficient basis for the resolution of international disputes.
Critiques of Forum Prorogatum
However, and perhaps unsurprisingly given the primacy traditionally granted to consent in international dispute settlement, the use of forum prorogatum has been criticised. Gupta has argued that “forum prorogatum has been used to strongarm the respondent state into conceding jurisdiction to the Court for fear of loss of face”, and Ayoub describes the emergence of the principle as “a flagrant act of judicial activism” (p.30), while also considering that it has since fallen “into an eternal slumber for which a death knell may have to be considered” (ibid).
But while forum prorogatum is evidently a gamble on the part of the Applicant, and most attempts at invoking it have failed, it lies not in an eternal slumber but instead like Sleeping Beauty awaits only the right conditions for awakening. Removing the possibility of forum prorogatum would do little to promote the peaceful settlement of international disputes. It is invoked sufficiently often that Applicants must see potential benefits, whether those be the final resolution of the dispute or political benefits as discussed below. And on the occasion when a Respondent accepts jurisdiction, consent has been clearly manifested. Now that the Rules set out a clear procedure for invoking forum prorogatum it is not, I would suggest, improper or activist simply for being unusual. As for the fear that States have been ‘strongarmed’ into accepting the Court’s jurisdiction, it seems clear from the record that this is not the case; since the introduction of Article 38(5) the majority of forum prorogatum attempts have simply been ignored.
Conclusion
The odds are therefore not in Vanuatu’s favour. The invocation of forum prorogatum has most often been met with silence, and despite France’s two prior acceptances there is little reason to expect Paris to break the pattern this time around. Djibouti and Congo addressed mutual legal assistance and criminal proceedings in French courts. Reasonably contained issues not raising any controversial questions of sovereignty; quite in contrast to the present case.
Yet it would be a mistake to read the Application only through the lens of its (probable) fate. Vanuatu recently spearheaded the Advisory Opinion on Climate Change, and understands that the strategic use of the Court’s procedures can be used to “to place pressure on politics”. Negotiations regarding the islands have been ongoing for several years, and the dispute is now framed openly as a legal one. French refusal to litigate it will become part of the public record, and this dispute may eventually follow the same path towards an Advisory Opinion as the Chagos Islands dispute between Mauritius and the United Kingdom. Vanuatu may not be Sleeping Beauty’s prince, but in time they may yet find their happily ever after.
Photo by Seiji Seiji on Unsplash
Juliette McIntyre
Juliette McIntyre is a Senior Lecturer in Law at Adelaide University and a specialist in international courts and tribunals. She holds a PhD from the University of Melbourne, which was nominated for the Harold Luntz and Chancellor's Prizes, and a first-class LL.M. from the University of Cambridge. Her scholarship has been cited before the International Court of Justice, and she has made over 350 media appearances regarding issues of international law. She is a co-host of the popular Called to the Bar: International Law Over Drinks podcast. She also really likes Stray Kids.
